I run a Kenwood DDX773BH. Best unit I have ever had to date. It's a couple years old now, and I'm sure there are newer versions out there, but this unit is still available. Good device for a not so high of a price.
I run dual camera's on this, front & back, and use decent aftermarket shielded HD cameras. Picture is outstanding, and you can control the cam direction views, with adjustable directional lines, or without.
The dude in this video is kind of annoying, but does give a detailed rundown of the features and use.